To make the question a bit more realistic let the following restrictions be assumed:
- the length of the mission is 50 years (roughly 1/2 human lifetime scale i.e. 50 years so that we get 30+ years to enjoy the results of our work!)
- brightness of the stars needs to be taken into account: stars will become fainter as the distance increases
- the diameter of the telescope used is limited to D=10m
- interferometric setups are allowed
Am I missing anything?